"Science is always a discourse"

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Detlef Günther, Vice President for Research and Corporate Relations. (Image: Pet

Detlef Günther, Vice President for Research and Corporate Relations. (Image: Peter Rüegg / ETH Zurich)

A number of researchers have published critical comments about an ETH Zurich study that generated a lot of interest with its quantitative assessment of the technical potential that reforestation holds for reducing CO2. In the following interview, Professor Detlef Günther, Vice President for Research and Corporate Relations, explains why he welcomes this discourse.

ETH-News: Professor Günther, ETH Zurich researchers working with Professor Tom Crowther’s group published a study this summer setting out a quantitative assessment of the carbon-cutting potential offered by reforestation. Today, numerous international scientists expressed criticism on the study . Isn’t that quite unusual? Detlef Günther: It’s certainly not unusual for researchers to take a different approach to testing a hypothesis. The scientific process is a continuous discourse that casts a critical light on new hypothesis.

But not every research triggers so many reactions... That’s true: the scale of the comments may have been unusual, but I think there were two reasons for this. First, climate change - and its possible solutions - is one of the most complex and most urgent challenges of our time. Therefore, the attention for this topic is very high. Second, the original study published by the Crowther Lab has elicited a massive response worldwide. Thus, it’s only logical that the results of the study are being scrutinised even more thoroughly by a very large scientific community, and as a consequence, the scientific discourse is more intense as well.

Some of the critical comments were made by researchers at ETH. Is there a lack of consensus on this topic even among our own scientists’ Every researcher approaches a research problem from a different angle, so it would be surprising if they all agreed. Scientific discourse must be encouraged within our university as well. Different perspectives and disagreements are essential if progress is to be made. ETH is one of the world’s top universities in the area of climate research. It’s therefore only logical for ETH scientists to take part in this debate, irrespective of whether the spotlight is on colleagues from their own university.

On the one hand, the comments question the technical aspects of the study, while on the other they are critical of the message: that planting trees is a way of halting climate change. Have the researchers of the Crowther Lab exaggerated this claim in their communication? One of the tasks of ETH researchers is to make their findings available to a broad public and thereby encourage societal discourse. This open communication of research results is always a balancing act. But the findings must meet the very highest scientific standards. In the responses they gave to the criticisms voiced, researchers in the Crowther Lab acknowledged that their communication was not always optimal. They are quite clear that reforestation is only one approach among many towards finding a solution. Even with this approach, CO2 emissions still need to be reduced in other ways. The authors have therefore made an appropriate amendment to the abstract of their original publication.

Does the criticism have any consequences for the authors of the study? They obviously need to engage with this discussion, and have already done so through their official response . They gave detailed replies to the points raised, clarified misunderstandings and also admitted some inaccuracies. That’s extremely important, as the debate about the necessary solutions to halt climate change are bound to be a constant concern for society in the future.

The study by the Crowther Lab on the potential that reforestation offers to reduce CO2 published (5 July 2019) prompted four scientific comments and three letters which were published in the October 18th edition, together with two responses of the scientists in the Crowther Lab. The authors have since amended a statement in the abstract of their original publication. Overview of the publications:

Bastin JF et al: The global tree restoration potential (amended abstract) How trees could save the climate (amended)

Veldman JW et al: Comment

Friedlingstein P et al: Comment

Lewis SL et al: Comment

Grainger A et al: Comment

Bastin JF et al: Response to comments

Luedeling E et al: (Letter) Forest restoration: Overlooked constraints

Delzeit R et al: (Letter) Forest restoration: Expanding agriculture

Sehil D et al: (Letter) Forest restoration: Transformative trees

Bastin JF et al: (Letter) Forest restoration: Transformative trees - Response

Simon Zogg